The royal couple also posed for "selfies" with some of the waiting crowd members.

The Duchess of Cambridge speaks to a young boy in the crowd at the Sydney Opera House.

Meanwhile Prince George received a special gift from Australia's Governor-General - a cuddly wombat.

Prince George, with his parents, receives a gift from the Governor-General. Credit: Commonwealth of Australia and Auspic

The eight-month-old prince is expected to make an appearance on Sunday when his parents take him to Sydney's Taronga Zoo where an enclosure housing bilbys - a rabbit-like marsupial - will be named after him.

The Duchess of Cambridge is greeted by well-wishers at the Sydney Opera House. Credit: DAN HIMBRECHTS/AAP/Press Association Images

William joked: "I suspect George's first word might be 'bilby' - only because koala is harder to say. We really look forward to our time here together as a family."